This is an application for a Fogarty International Center K01 International Research Scientist Development Award for Dr. Michael Vinikoor, an infectious diseases physician at the University of North Carolina at Chapel Hill (UNC). Dr. Vinikoor has shown great promise as a young investigator in the area of HIV/hepatitis B virus (HBV) co-infection in sub-Saharan Africa (SSA); however, as many in his position, he requires dedicated support to ensure his successful career development. This award will provide Dr. Vinikoor with the necessary support to accomplish the following goals: (1) to become an expert in viral hepatitis, (2) to become an expert in clinical research implementation in resource-constrained settings, (3) to gain additional knowledge and skills in advanced study design and biostatistical methods, and (4) to develop skills in multi- disciplinary, long-distance collaboratin. To achieve these goals, Dr. Vinikoor has assembled a highly experienced mentorship team comprised of Dr. Michael Fried (U.S. Primary Mentor), Professor of Medicine and Director of the Liver Clinic at UNC, Dr. Benjamin Chi (Zambia Primary Mentor), Chief Scientific Officer of Centre for Infectious Disease Research in Zambia and Associate Professor of Obstetrics and Gynecology at UNC, as well as three Co-Mentors: Dr. Joseph Eron, expert in clinical and translational HIV research as well as in multi-center international clinical trials, Dr. William Miler, an expert in analytic methods and mentoring young investigators toward research independence, and Dr. Charles van der Horst, an expert in global health and in interdisciplinary research collaborations. Liver disease due to viral hepatitis has become a leading cause of death of HIV-infected individuals receiving antiretroviral therapy (ART) in upper-income settings. In sub-Saharan Africa (SSA), an estimated 3 million HIV-infected patients have chronic HBV co-infection. Compared with upper-income settings, the outcomes of HIV/HBV may be different in SSA due to diverse patterns in HBV transmission, environmental exposures, and hepatotoxic co-infections. Leveraging an existing NIH-funded cohort in Zambia, Dr. Vinikoor's supported research will comprise two main components. First, he will assess the prevalence of significant liver fibrosis in patients with HIV/HBV using non-invasive methods including transient elastography. Predictors of fibrosis will assessed including alcohol and herbal medication and co-infections such as schistosomiasis and hepatitis D infection. Then Dr. Vinikoor will measure changes in liver fibrosis during 3 years of longitudinal follow-up and analyze factors that predict improvement in fibrosis, include HIV and HBV viral suppression, patterns of alcohol use, and CD4+ immune recovery. Additional HBV end-points such as hepatocellular carcinoma and liver decompensation will also be ascertained. The studies outlined in this proposal will generate currently unavailable data on the outcomes of these at-risk patients, and will inform and optimize HIV/HBV treatment guidelines for resource-constrained settings. They also provide an ideal training platform for a young investigator seeking to establish a career in HIV/HBV infection and will provide key epidemiologic data needed for future interventional trials in this critical field.